HARTFORD, Connecticut — A judge on Tuesday ordered a Connecticut teenager accused of fatally stabbing a classmate on the day of their prom to be examined by a psychiatrist hired by the state, after his lawyers announced they were pursuing an insanity defense.

Christopher Plaskon, 17, appeared briefly in Milford Superior Court. He is charged with murder in the stabbing of 16-year-old Maren Sanchez in a hallway at Jonathan Law High School in Milford in April 2014.

Judge Frank Iannotti approved a motion by Milford State's Attorney Kevin Lawlor to allow the prosecution to have its own expert evaluate Plaskon's mental health and continued the case to July 7. The order came after Plaskon's lawyers filed notice Monday that they were planning a defense of "mental disease or defect and/or extreme emotional disturbance."

Lawlor indicated in court documents that the state would hire a Yale University forensic psychiatrist.

Richard Meehan, an attorney for Plaskon, said experts hired by the defense examined Plaskon, but he declined to say what they found. Meehan has said Plaskon was taking anti-psychotic and anti-anxiety medications.

"The focus here is on mental status," Meehan said after the court proceeding.

Police have said they were looking into whether the attack was related to Sanchez's refusal to be Plaskon's date to the junior prom.

Sanchez, a member of the National Honor Society who was active in drama and other school activities, had been focused on prom in the days before her death. She had posted a photograph on Facebook of her blue prom dress and was looking forward to attending with a new boyfriend.

Authorities say Plaskon attacked Sanchez in a hallway on the morning of the prom, stabbing her in the neck and torso. Afterward, Plaskon told a police officer: "I did it. Just arrest me," according to police.

Plaskon, who is detained on $3 million bail, is being tried as an adult and faces up to 60 years in prison if convicted of murder.

If found not guilty by reason of insanity, he could be detained for 60 years at the state's maximum-security psychiatric hospital in Middletown or possibly released years earlier if doctors determine he is no longer a danger to himself or others.

Plaskon pleaded not guilty last year and chose a trial before a three-judge panel instead of a jury.

Anthony Bonadies, a lawyer for Sanchez's father, Jose Sanchez, attended the court hearing Tuesday while his client was in Florida.

"Mr. Sanchez ... is committed to stay the course to make sure that Maren's life is front and center during the proceedings," he said. "She needs to remain in the hearts and minds of whoever the decision-makers will be, so there's accountability for her death and justice."